/**
  * Approves a CERF by deleting all other pending CERFs for the same event.
  *
  * @param $id
  * @return \Illuminate\Http\RedirectResponse
  */
 public function approve($id)
 {
     $cerf = Cerf::find($id);
     $cerf->update(['approved' => true]);
     $otherCerfs = Cerf::where('event_id', $cerf->event_id)->where('approved', false)->get();
     foreach ($otherCerfs as $cerf) {
         // See comments in CerfsController@destroy.
         DB::statement('delete from cerfs where id=' . $cerf->id);
         DB::statement('delete from events_assigned_tags where cerf_id=' . $cerf->id);
     }
     return redirect()->action('CerfsController@overview');
 }